1. The Field of the Invention
The present invention relates generally to wireless networks. More specifically, the present invention relates to devices networked together by an infrared link. Even more specifically, the present invention relates to methods and apparatus for communicating between peripheral devices via multi-directional infrared transmissions.
2. The Relevant Technology
Infrared (IR) transmission is wireless communication over a relatively small area, using infrared components to transmit and receive signals. Infrared transmissions require line-of-sight connection between the transmitter and receiver or between each of these and a common target. Line-of-sight connection usually means about 1 meter in centerline distance between communicating IR ports with a field-of-view of about xc2x130xc2x0 therefrom.
One problem, however, is that achieving line-of-sight connection is often inconvenient. For example, many infrared ports, i.e., an infrared transmitter and receiver pair, are assembled into personal computers (PC) for communicating with a peripheral device, such as a personal data assistant (PDA), along a base portion of the PC on a side behind the flip-up display screen. Then, if the PC is positioned on a desktop facing a wall, as commonly occurs, the PDA would need to be positioned generally between the wall and PC in order to allow IR transmissions to transpire.
Moreover, this becomes impracticable in other computing environments, such as in planes and automobiles, because PC""s are placed on human laps and are pinched between other humans, adjacent seats, doors, etc., and little if any physical berthing exists for placing another device with an IR port into a line-of-sight arrangement. Consequently, achieving communications between IR ports is a function of having adequate space to arrange the ports so that critical juxtapositioning therebetween can be achieved.
Another problem is that many devices which contain software, or are able to implement software suitable for communicating via IR transmissions, are not presently configured with any IR ports. Some conventional retrofitting devices, however, do address this problem. Yet, these are expensive and/or have complex or burdensome interfacing requirements such as awkward platforms, excessive cabling and onerous mating connectors.
In general, IR transmission signals are either focused or diffuse. A focused signal is aimed directly at its recipient whereas a diffuse signal disperses and travels in multiple directions. As such, to achieve greater range focused signals are required, but with focused signals comes the requirement of critical juxtapositioning of the communicating IR ports. Whereas, to achieve greater field-of-view and looser alignment between communicating IR ports, diffuse signals are required. With diffuse signals, however, the ports must be closer.
Accordingly, it would be an advance to provide improved IR ports that overcome the foregoing alignment, power and retrofitting disadvantages.
It is, therefore, an object of the present invention to provide a multi-directional IR port that is economically and easily adapted to a variety of existing computing system configurations.
It is another object of the present invention to provide a multi-directional IR port having advantage over conventional ports with greater range while allowing for less critical juxtapositioning during infrared communications.
It is still another object of the present invention to provide a multi-direction IR port allowing flexibility in berthing requirements between communicating devices when achieving line-of-sight connections.
In accordance with the invention as embodied and broadly described herein, the foregoing and other objectives are achieved by providing methods and apparatus for wirelessly communicating between a master and slave device with multi-directional infrared transmissions.
In a preferred embodiment, the master device is equipped with a multi-directional infrared (IR) port in the form of either a PCMCIA communications card, an infrared domed housing or a plurality of IR ports, aimed multi-directionally, about a computing system configuration. In general, the IR port has a plurality of IR pairs, infrared isolated therebetween, comprised of an infrared transmitter and receiver. From the master device, each of the IR transmitters of each IR pair transmits an attention pulse in a wide-angular pattern in a singular plane to attract the attention of the slave device, regardless of its physical placement in relation to the master device. In response to the attention pulse, the slave device sends a reply. Thereafter, the reply is evaluated at each of the IR pairs according to various criteria to select the IR pair or IR pairs best suited for infrared communications with the slave device. Preferably, the IR pair(s) are selected so that the fastest, most accurate and/or strongest signal strength communications are effectuated between the master and slave devices.
Once the IR pair providing the desired infrared communication characteristics is selected, the physical placement of the slave device is stored and associated with that IR pair. In this manner, since these devices are infrequently moved in relation to one another, future infrared transmissions between the master and slave device are quickly accomplished because the physical relation to one another is known and stored. The association between master and slave device is preferably stored in a look-up table to which the master device has readied access. Thereafter, the other IR pairs are inactivated and infrared transmissions of data between the master and slave devices are performed.
It is a feature of this invention that devices not equipped with infrared transmission capabilities are easily and readily retrofitted with either of the foregoing apparatus in order to economically and efficaciously achieve infrared transmissions.
It is another feature of this invention that because each of the IR pairs are infrared isolated from one another, substantially simultaneous infrared transmissions may occur between a plurality of uniquely addressed peripheral (slave) devices. Substantially simultaneous infrared transmissions are also attainable by multiplexing the biasing of each of the IR pairs.
It is still another feature of this invention, in the event that either the master or slave is not equipped to communicate with this style of infrared transmissions, that each device may downgrade to conventional infrared transmission technologies. Preferred troubleshooting procedures are also described in the event the master cannot locate the slave device.
These and other objects and features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.